The invention relates to apparatus for exchanging heat such as the cooling of electronic assemblies or components adapted for slide-in circuit applications arranged one above the other in racks. More particularly, it relates to apparatus which supplies cooling air to the individual slide-in circuits from their respective underside, the air leaving the respective slide-in after having been heated therein.
Conventional apparatus is known from German Pat. No. 11 03 433 which serves for the removal and deflection of the cooling air--guided through housings and cabinets of heat-generating equipment, preferably electrical equipment, from below--by means of an angled-on guide surface comprising a part or the very top covering with lateral cheeks to prevent lateral escape of cooling air. In this known device, the plate type guide surface provided for the outgoing cooling air or respectively, in the case of housings set one above the other, for the outgoing and incoming cooling air can be directed into the plane of the housing edge by its lateral cheeks pivoting about pivot pins provided near the upper housing edge. Due to this construction, with housing or slide-in compartments located one above the other, there is achieved only a cooling air flow from the respective front to the respective back through the respective housing or through the respective slide-in compartment. This means that cooling air of different temperature is available for the housings arranged at different levels, so that the cooling effect will be very different for the various housings.
Then also a cooling device referred to as a heat exchange for electronic systems, for example in U.S. Pat. No. 3,730,264, where in a rack for receiving several slide-in circuit boards (also simply called slide-ins) lying one above the other a V-shaped baffle plate is provided between pairs of slide-in rows, wherein the baffle plate is formed so that it prevents the heat escaping upward from the lower slide-in from entering the entrance zone of the slide-in thereabove, in such a way that the warm air emerging from all slide-in compartments comes out on one and the same rack side, e.g. the back. It therefore becomes a disadvantage of this conventional cooling system that the slide-ins present at different levels are supplied with cooling air of different temperature and hence are subjected to different cooling effects.
Another cooling device is disclosed in U.S. Pat. No. 3,874,474 where in a rack several slide-in compartments are stacked one above the other with separating sheets being arranged between slide-in compartments lying directly one above the other, in such a manner to provide for the removal warm air exiting from the respective lower slide-in toward the back of the rack while at the same time permitting the introduction of cold air from the front of the rack into the next higher slide-in. Thus this known device also has the deficiency that has been pointed out in connection with the other conventional device previously discussed.
Still another conventional arrangement is a multi-level encapsulated switch panel with a ventilation arrangement, see German patent document No. 27 55 811, wherein the arrangement has been subdivided into several compartments, each having a front door and containing equipment. The front door is provided with an air inlet, and the sides of the compartment are formed as a path for the outgoing air. Again it is a known disadvantage in the switching field that due to the different temperature of the cooling air the cooling effect is different for the equipment located at different levels.
It is also known to use a system for removing the heat of dissipated power from electronic equipment slide-in boards installed in a cabinet rack (DE-AS No. 29 39 088) where the respective equipment slide-ins seal off by their front panels the entire cabinet front and moreover are connected by natural convection with an air flue leading to the top side. The slide-ins to be cooled also have horizontal chassis bottoms with horizontal finned cooling units applied thereon, whose cooling channels extend from the front to the back of the cabinet and open into the flue formed on the back of the cabinet. At the front plates of these slide-ins to be cooled, air inlet openings leading to the cooling channels of these finned cooling units are provided. Again it is a disadvantage of this known system that for the cooling of the equipment slide-ins arranged at different levels of the cabinet rack cooling air of different temperature is available, owing to which the cooling effect at the different levels will again be different.
Lastly according to European patent application 0 020 084, there is disclosed an electronic rack assembly cooled via natural air convection, with at least compartments which are arranged one above the other so that they define an interspace between them. At least one air flow port opening into the interspace is provided in the top side of the lower case, and further at least one air flow port opening into the interspace is provided in the bottom side of the upper case. Finally at least one arrangement for channeling the air from the respective port in the lower case to at least one outlet opening and for channeling air from at least one inlet opening toward the respective opening in the upper case is provided. The inlet openings and the outlet openings are arranged in different areas of the front side of the interspace. The air channeling means comprises a separating means which divides the interspace into upper and lower compartments which are in flow communication with the openings of the respective upper or lower case. One of said compartments is arranged so that it is in flow communication directly with the front side of the interspace. From an opening a passage extends through said one compartment into the separating means, to connect the other compartment with the front side of the interspace. The separating means and the respective passage are arranged so that the upper compartment is in flow communication only with one or more feed openings in a lower area at the front side of the interspace and that the lower compartment is in flow communication only with one or more outlet openings above the respective inlet opening in an upper area at the said front side of said interspace. Thus also this known electronic rack has the same deficiency that has been pointed out in connection with the other conventional arrangements discussed in the foregoing.
It is, accordingly, an object of the invention to show a way how a device of the initially mentioned kind can be designed to make sure at relatively little cost that cooling air of practically the same temperature can be supplied to the slide-in compartments and associated equipment located at different levels of the rack or respectively to electronic assemblies or components, so that for all electronic assemblies or components to be cooled experience the same cooling effect.